JPH01126603A - Optical fiber line light - Google Patents

Abstract

PURPOSE:To uniformize the quantity of the light emitted from a line part by intersecting the light exist end face of a line part and the light incident end face of a point part with each other and specifying the angle theta between the longitudinal direction of the line part and the optical fiber axis of the line part. CONSTITUTION:The light exist end face of the line part and the light incident part of the point part of the line pint light which is formed by converging th ends, on one side, of many pieces of the optical fibers 3 to a bundled shape to constitute the point part to serve as the incident end of light and arraying the ends, on the other sides, to a line shape to constitute the line part to serve as the exist end of light are so disposed as to intersect with each other and the angle theta between the longitudinal direction of the line part and the axis of the optical fibers 5 disposed in the line part is specified to 0 deg.<theta<90 deg.. The emission of the light of the higher modes by bending of the optical fibers is thereby prevented and the light to be emitted from the line part is uniformized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application J] The present invention relates to a line point light that can be used as a line-shaped light source that can be used in a defect inspection device for sheet-like objects.

As a defect inspection device for sheet-like objects, a moving sheet-like object is irradiated with a line-shaped light source, the anti-M light or transmitted light is read by a line COD camera, and image processing is performed to detect defects contained in the sheet-like object. Equipment for inspecting defects such as scratches and foreign matter has been developed and is now being used in many places.

Line light sources used in such fields are required to have the following performance.

1) High brightness.

2) The amount of light emitted from the line part is uniform.

3) The sheet material is often made of a material that is sensitive to heat and must be a cold light source.

[Conventional technology]

Generally, the following three methods are known as methods for obtaining a line-shaped light source.

1 is a fluorescent lamp, and a light source for a defect inspection apparatus for sheet-like materials is one that operates at a high frequency of about 30 kHz.

Part 2 is a line-shaped halogen lamp, and Part 3 is a line point light made of optical fiber.In this optical fiber line point light, one end of a large number of optical fibers is bundled into a cylindrical shape, and the other end is A linear light source is obtained by arranging them one by one in a line and emitting light incident from the cylindrical part from the linear end face.

[Problem that the invention seeks to solve]

A line-shaped light source made of a fluorescent lamp has a uniform amount of emitted light and generates little heat, but it is difficult to make it into a bulky light source, and a line-shaped halogen lamp can provide high brightness, but it generates less heat. There was a problem. In addition, line point lights made from optical fibers have high brightness and are a cold light source, but the amount of light emitted from the line part may have light source irregularities caused by the lamp that serves as the light source, and if the optical fiber is used as a line point light, There is a problem of large unevenness in light intensity due to unevenness in the light intensity distribution due to changes in the angle of light emission from the line portion due to differences in the bending angle of the optical fiber during processing. Further, although it is possible to uniformize the amount of light emitted from the line portion by performing scattering treatment on the end face of the line portion of the optical fiber line light, there is a problem in that the brightness is significantly reduced.

[Means for solving problems]

Therefore, the present inventors conducted studies with the aim of developing a line point light made of optical fiber that is useful as a line light source and does not have the above-mentioned difficulties, and found that the line point light that has been developed in the past. In the π-line light, optical fibers arranged in a line are defined as the point part where one end of a large number of optical fibers is bundled as the light input end, and the line part arranged in a line shape on the other end as the light output end. This type of line light is limited to those in which the optical fiber arrangement angle formed by the arrangement direction of the optical fibers arranged in a line and the line part formation direction is 90 degrees, and this type of line light is such that the incident light is in a higher order mode due to the bending of the optical fiber. It was discovered that unevenness in the light intensity distribution due to the bending angle of the optical fiber is directly emitted as light intensity unevenness in the line section, and in order to create a line light without such inconvenience, it is necessary to change the alignment angle of the optical fiber with respect to the line direction. They discovered that the object could be achieved by arranging them at a certain angle θ, and completed the present invention.

The gist of the present invention is that one end of a large number of optical fibers is converged into a bundle to form a point portion that serves as the light input end, and the other end is arranged in a line to form a line portion that serves as the light output end. This is a line point light, in which the light emitting end surface of the line part and the light incident part surface of the point part are arranged to intersect with each other, and the longitudinal direction of the line part and the optical fiber axis arranged in this line part are arranged. A line point light made of optical fiber is characterized in that the angle is 0° and θ<90°.

The present invention will be explained in more detail with reference to Examples below.

〔Example〕

FIG. 1 is a diagram for explaining a line point light of the present invention using a large number of circular optical fibers.

Figure 1(a) is a perspective view of the line point light.
B) is a diagram in which the axis of one optical fiber (5) arranged in a line portion is inclined by θ with respect to the length direction of the line.

In the figure, (1) is the end face of the optical fibers arranged in the line direction, and in this example, the optical fibers (3) are arranged in two stages in the line part, and the upper part shows the shape of the optical fiber axis with respect to the line direction. Angle θ is 60°, lower row is 120°
It was set to (2) is a line part base, and (4) is a point part base which is the converging end of the optical fiber. (5) is the end face of the point optical fiber. In order to reduce the influence of light source irregularities on the light emitted from the line section, the optical fibers in the line section and the bundle section are arranged randomly with respect to each other.

FIG. 2 shows unevenness in the output angle light amount distribution due to bending of the optical fiber when the angle θ between the length direction of the line portion and the optical fiber axis at the core portion is 90°.
It can be seen that the emitted light is in a higher order mode.

FIG. 3 is a diagram showing an example of a defect inspection apparatus for a sheet-like object, which is one application of the line point light of the present invention.

A sheet-like object (6) to be inspected is illuminated by light emitted from a line portion of an optical fiber line point light (7), and is traveling at a constant speed. The reflected light from the inspection object (6) is read by the line c c D (8), and the signal is processed by the image processing device (9) to detect defects included in the inspection object. Defect data processing, alarm output, etc. are performed by microcomputer 0[D.

FIG. 4 shows a light radiation pattern when the angle θ between the direction of the axis of the optical fiber disposed in the line portion and the length direction of the line portion is 60°.

Figure 5 shows the linear arrangement direction and the optical fiber angle of 9.
When a 0° line light is used, the rise angle of the CCD output around 0, which is the output signal of the line COD, is high, but there is also fluctuation at the center. 1/2 range in the center of Fig. 5 (CCD elements 8111025 to Na307
The variation in CCD output values in 2) was ±11.3%. Since the output pattern of one optical fiber is as shown in FIG. 2, it is visually observed that the light is illuminated in a ring shape.

Note that the measurement conditions are as follows.

1) The optical fiber line point light used a large number of polymethyl methacrylate optical fibers (diameter 200M), the line part length was 320III, and the angle between the length direction of the line and the alignment axis of the optical fibers was 90°.

2) COD The number of elements was 4096, the scanning period was 30 rls, and the field of view was 400 fields.

3) Lens a) Focal length f=50■ b) Aperture F-5, 6 4) Distance between CCD and inspection object 700 Figure 6 shows the relationship between the length direction of the line section and the optical fiber arrangement axis. It is an output signal of the line CCD of the optical fiber line point light of the present invention with an angle of 60°. Comparing with FIG. 5, it can be seen that although the rising angle of the CCD output at the periphery is low, uniform output light with no fluctuation at the center is obtained. The measurement conditions were the same as in Figure 5.
The variation in output values was improved to ±8.8%. Moreover, even by visual inspection, it is no longer possible to observe the ring-shaped illumination that was observed with the line point light as shown in FIG.

In the present invention, in addition to the line point light using a circular optical fiber as described above, it is possible to use an optical fiber with a diameter of 0.1 to 3 mm as well as an optical fiber with a diameter of 5 to 200 μm. A similar effect can be obtained by using a plastic multifilament optical fiber having a substantially rectangular or circular cross-sectional shape, in which the affected parts of the core-sheath structure are arranged in the sea at a ratio of 50 to 1000 pieces.
The length of the line part can be adjusted to any length according to the width of the object to be inspected.

The width of the line portion allows the optical fibers in the line portion to be stacked not only in one stage but in multiple stages.

It is also possible to arrange the line portions in multiple stages and change θ depending on the number of stages.

〔Effect of the invention〕

The line point light of the present invention has extremely large unevenness in the amount of light emitted from the line part of conventionally developed line point lights. By arranging the optical fiber axis at an angle of θ with respect to the line length direction of the point light, as shown in Figure 4, we have succeeded in preventing the output light from becoming a higher order mode due to bending of the optical fiber. The light emitted from the line part is made uniform, making it a line point light that exhibits excellent performance.

[Brief explanation of the drawing]

FIG. 1(6) is a perspective view showing an example of an optical fiber line point light of the present invention, and FIG. 1(b) is a plan view showing an example of an optical fiber arranged at an angle θ in the line portion. , FIG. 2 shows the light intensity distribution of the light emitted from the optical fiber arranged in the line part of a conventionally developed line point light, and FIG. 3 shows an example of the application of the line point light of the present invention. , Fig. 4 shows the light intensity distribution diagram of the light emitted from one optical fiber arranged in the line part of the line point light of the present invention, and Fig. 5 shows the light intensity distribution diagram of the light emitted from the line part of the line point light used conventionally. Figure 6 shows the output signal when the light emitted from the line part of the line point light of the present invention is measured using a CCD. . Figure 1 Figure 2 Toshikamouchi (・) Figure 4 Figure 5 Figure 6

Claims (2)

[Claims] (1) A line point light is a line point light in which one end of a large number of optical fibers is bundled to form a point part that serves as the light input end, and the other end is arranged in a line and has a line part that serves as the light output end. The light output end face of the part and the light input end face of the point part intersect, and the angle θ between the length direction of the line part and the optical fiber axis of the line part is 0°<θ<90°. Features: Optical fiber line point light. (2) Claims that use a plastic multifilament optical fiber in which 50 to 10,000 islands of a core-sheath structure with a diameter of 5 to 200 μm and optical transmission properties are arranged in the sea. The optical fiber line light described in item 1.